JP7622864B2 - Mass spectrometry data analysis method and imaging mass spectrometry apparatus - Google Patents

Description

The present invention relates to an imaging mass spectrometer and a method for analyzing data collected by an imaging mass spectrometer.

An imaging mass spectrometer is a device capable of visualizing the distribution of compounds on a sample such as a biological tissue slice. The imaging mass spectrometer disclosed in Patent Document 1 is equipped with an ion source that uses the matrix-assisted laser desorption/ionization (MALDI) method, and collects mass spectrum data over a predetermined mass-to-charge ratio range (strictly speaking, this is the italicized "m/z", but in this specification it is conventionally referred to as "mass-to-charge ratio" or simply "m/z") for each micro-area that finely divides a two-dimensional measurement area on the sample.

Another method of imaging mass spectrometry is known, which uses a sampling method called laser microdissection to cut out sample pieces from each micro-area within the measurement region, and then provides a liquid sample prepared from each sample piece to a mass spectrometer to obtain mass spectrum data for each micro-area (see Patent Document 2). Here, devices that use such a sampling method are also included in the imaging mass spectrometer.

In any case, in the imaging mass spectrometer, for example, the signal intensity value at the m/z value of an ion derived from a specific compound is extracted from the mass spectrum data obtained for each micro-region on the sample, and an image is created in which the signal intensity values are arranged according to the two-dimensional position of each micro-region on the sample, thereby obtaining an image showing the distribution of the specific compound. Hereinafter, such an image is referred to as an MS (Mass Spectrometry) imaging image.
In a typical imaging mass spectrometer, when the compound to be observed, i.e. the target compound, is determined, the user specifies the m/z value corresponding to that compound, and then an MS imaging image at that m/z value is created and displayed on the display screen.

On the other hand, if the target compound has not been identified, the user selects an appropriate mass peak while viewing the acquired mass spectrum. The imaging mass spectrometer then creates an MS imaging image corresponding to the m/z value of the selected mass peak and displays it on the display screen.

As described in Patent Document 1, in such cases, the mass spectrum used by the user to select a mass peak is often an average mass spectrum created by averaging multiple mass spectra obtained for all the micro-regions in the measurement region, or an integrated mass spectrum created by simply integrating the multiple mass spectra. This is because it is generally believed that information about all compounds present in the measurement region is reflected in the average mass spectrum or integrated mass spectrum (the average mass spectrum and the integrated mass spectrum are essentially the same, so in the following explanation, only the average mass spectrum will be mentioned, but the same is true for the integrated mass spectrum).

JP 2011-191222 A International Publication No. 2015/053039

However, the above analysis method using conventional imaging mass spectrometers has the following problems:

The average mass spectrum described above is an averaged version of so-called profile spectra, which are created based on the raw data obtained by mass analysis of each small area within the measurement region. The width of the mass peaks observed in the profile spectrum depends on the mass resolution of the mass analyzer used for the measurement.

In time-of-flight mass spectrometers (TOFMS), which are commonly used in imaging mass spectrometers, the mass resolution is generally relatively high, but the tails of mass peaks appearing in the profile spectrum may be broad. In such cases, if the difference in m/z value between a mass peak observed in a relatively wide region within the measurement region and a mass peak observed locally in a narrow region within the measurement region is small, and the signal intensity of the latter mass peak is significantly smaller than that of the former mass peak, when the mass spectrum is averaged or integrated, the mass peak with the smaller signal intensity may be buried in the tail of the mass peak with the larger signal intensity. In such cases, the mass peak observed locally does not appear in the average mass spectrum, and as a result, the user may miss important compounds that are unevenly distributed within the measurement region.

In addition, the mass resolution of a typical TOFMS may not be sufficient to separate mass peaks from different compounds with very close masses. When an average mass spectrum is created from multiple profile spectra with such insufficient separation, mass peaks with close m/z values often overlap and essentially become a single mass peak. The m/z value obtained from such a mass peak may differ from the m/z value corresponding to any of the multiple overlapping compounds.

As mentioned above, it is not rare that mass peaks derived from compounds present locally and in trace amounts on a sample cannot be observed in an average mass spectrum. In addition, the m/z values of mass peaks observed in an average mass spectrum often differ from the m/z values corresponding to compounds actually contained in the sample. For this reason, if a mass peak observed in an average mass spectrum is selected and an MS imaging image at a specific m/z value corresponding to it is displayed, the distribution of compounds that the user should have observed may be inaccurate.

The present invention has been made to solve these problems, and one of its objectives is to provide a mass spectrometry data analysis method and an imaging mass spectrometry apparatus that can reliably identify the presence of compounds that are present in relatively small amounts locally within the measurement area without overlooking them, and can confirm MS imaging images.

Another object of the present invention is to provide a mass spectrometry data analysis method and an imaging mass spectrometry apparatus that can display MS imaging images of m/z values that accurately correspond to compounds present in the measurement region.

One aspect of a mass spectrometry data analysis method according to the present invention, which has been made to solve the above problems, is a mass spectrometry data analysis method for analyzing data obtained by performing mass spectrometry on each of a plurality of micro-areas within a measurement area on a sample, comprising the steps of:
an analysis region determination step of determining a plurality of analysis regions each including a plurality of the microregions by dividing the measurement region or in response to a user's designation within the measurement region;
a spectrum calculation step of averaging or integrating profile spectra for each of a plurality of micro-regions included in one analytical region based on data obtained for the micro-regions in each of the plurality of analytical regions to obtain an individual integrated mass spectrum;
a peak information integration step of detecting peaks in each of the plurality of individual integrated mass spectra, collecting peak information including at least the mass-to-charge ratio values of the detected peaks in each of the plurality of analysis regions, and collecting the peak information of the plurality of analysis regions and arranging peaks that can be estimated to have substantially the same mass-to-charge ratio value to obtain integrated peak information;
an information display step of creating and displaying a peak list or a mass spectrum based on the integrated peak information;
It has the following characteristics.

In addition, one aspect of the imaging mass spectrometer according to the present invention, which has been made to solve the above problems, is
a measurement unit for acquiring data by performing mass spectrometry on each of a plurality of micro-areas within a measurement area on a sample;
an analysis region determination unit that determines a plurality of analysis regions each including a plurality of the microregions by dividing the measurement region or in response to a user's designation within the measurement region;
a spectrum calculation unit that averages or integrates profile spectra based on data obtained by the measurement unit for a plurality of micro-areas included in each of the plurality of analysis regions to obtain an individual integrated mass spectrum;
a peak information integration unit that performs peak detection for each of the plurality of individual integrated mass spectra, collects peak information including at least the mass-to-charge ratio value of the detected peak in each of the plurality of analysis regions, and collects the peak information of the plurality of analysis regions and organizes peaks that can be estimated to have substantially the same mass-to-charge ratio value to obtain integrated peak information;
a display processing unit that creates a peak list or a mass spectrum based on the integrated peak information and displays it on a display unit;
It is equipped with the following.

In the above aspect of the present invention, the profile spectra are averaged (or integrated) for each analysis area, which is a smaller area than the entire measurement area where data was collected, and integrated peak information is obtained based on the results. This makes it possible to prevent peaks derived from compounds that are present in relatively small amounts locally within the measurement area from being buried in the tails of other peaks with similar m/z values and high intensities, and provides the user with a peak list or mass spectrum that accurately reflects such peaks. As a result, according to the above aspect of the present invention, the user can accurately analyze the compound of interest without overlooking the presence of compounds that are present locally in small amounts in a narrow range within the measurement area.

Furthermore, according to the above-mentioned aspect of the present invention, it is possible to display a mass spectrum in which peaks of m/z values corresponding with high accuracy to the masses of multiple compounds present in the measurement region are observed while taking advantage of the high mass accuracy of the mass spectrometer used for the measurement. This allows the user to observe high-accuracy MS imaging images corresponding to each of the multiple compounds, and to perform more detailed and accurate compound distribution analysis than ever before.

1 is a schematic block diagram of an imaging mass spectrometer according to one embodiment of the present invention; FIG. 2 is an explanatory diagram of a measurement state on a sample in the imaging mass spectrometer of the present embodiment. FIG. 4 is a diagram showing an example of the distribution state of compounds in a measurement area on a sample. FIG. 4 is an explanatory diagram of an example of data analysis processing in the imaging mass spectrometer of the present embodiment. FIG. 13 is a diagram showing a modified example in which a plurality of analysis regions are set within a measurement region in the imaging mass spectrometer of the present embodiment.

Below, one embodiment of the imaging mass spectrometer and mass analysis data analysis method related to the present invention is described with reference to the attached drawings.

FIG. 1 is a schematic block diagram of an imaging mass spectrometer according to this embodiment.
The imaging mass spectrometer of this embodiment includes an imaging mass spectrometer section 1 , a data processing section 2 , an input section 3 , and a display section 4 .

The imaging mass spectrometry unit 1 is, for example, the measurement unit of an atmospheric pressure MALDI ion trap time-of-flight mass spectrometer (APMALDI-IT-TOFMS). However, the imaging mass spectrometry unit 1 may also be a device that combines a laser microdissection device, as disclosed in Patent Document 2, with a mass spectrometer that performs mass analysis on a sample prepared from a minute sample piece collected from the device by the laser microdissection device.

The data processing unit 2 mainly has the function of processing the large amounts of data obtained by the imaging mass spectrometry unit 1, and includes as its functional blocks a data storage unit 20, a region division unit 21, a profile spectrum creation unit 22, a spectrum averaging unit 23, a peak information collection unit 24, a peak information integration unit 25, a peak list display processing unit 26, a peak selection instruction receiving unit 27, an MS imaging image creation unit 28, an image display processing unit 29, etc.

In the imaging mass spectrometer of this embodiment, the data processing unit 2 is usually configured around a personal computer or a more powerful workstation, and the above-mentioned functional blocks can be realized by executing dedicated data processing software (computer program) installed on the computer. In this case, the input unit 3 is a keyboard and a pointing device (such as a mouse) attached to the computer, and the display unit 4 is a display monitor.

The computer program can be provided to the user by storing it on a computer-readable, non-transitory recording medium, such as a CD-ROM, DVD-ROM, memory card, or USB memory (dongle). The program can also be provided to the user in the form of data transfer via a communication line, such as the Internet. Furthermore, the program can be pre-installed in a computer that is part of the system (strictly speaking, a storage device that is part of the computer) when the user purchases the system.

An example of the data analysis process in the imaging mass spectrometer of this embodiment will be described with reference to FIGS.
Fig. 2 is an explanatory diagram of the measurement state by the imaging mass spectrometer 1. Fig. 3 is a diagram showing an example of the distribution state of compounds in a measurement region on a sample. Fig. 4 is an explanatory diagram of an example of data analysis processing in the imaging mass spectrometer of this embodiment.

The measurement target of the imaging mass spectrometry unit 1 is, for example, a thinly sliced biological tissue sample such as the brain or internal organs of an experimental animal. Such a sample is placed on a sample plate, the surface of which is coated with a matrix for MALDI, and the plate is then set at a predetermined position in the imaging mass spectrometry unit 1.
2, the imaging mass spectrometry unit 1 performs mass analysis on each of micro-areas 102 obtained by dividing a predetermined measurement area 101 set on a sample 100 into small areas in a grid pattern, and acquires mass spectrum data over a predetermined m/z range. The position, size, shape, etc. of the measurement area 101 can usually be appropriately determined by the user through optical microscope observation, etc.

The specific analysis operation is as follows. The ion source in the imaging mass spectrometry unit 1 irradiates one micro-region 102 with laser light for a short time, generating ions derived from compounds present in the micro-region 102. The generated ions are once introduced into an ion trap, then sent to a time-of-flight mass separator where they are separated according to their m/z values and then detected. This detection signal is mass spectrum data corresponding to one micro-region 102. As shown in FIG. 2, this mass spectrum data is data (profile spectrum data) that shows a continuous waveform on the m/z axis. By repeating the same analysis operation while moving the sample 100 or the ion source so that the irradiation position of the laser light moves on the sample 100, mass spectrum data can be collected for each of the micro-regions 102 set within the measurement region 101.

Instead of performing conventional mass analysis on each micro-region 102, MS/MS analysis, in which ions having a specific m/z value or falling within an m/z range are dissociated and analyzed by collision-induced dissociation or the like, or MS ⁿ analysis, in which n is 3 or greater, may be performed to obtain product ion spectrum data.

The set of mass spectrum data for each micro-region 102 collected as described above, i.e., the MS imaging data for the entire measurement region 101, is transferred from the imaging mass spectrometry unit 1 to the data processing unit 2 and temporarily stored in the data storage unit 20. The data at this time is raw data obtained by mass spectrometry, but the data may be stored in the data storage unit 20 after appropriate waveform processing such as predetermined noise removal has been performed on this raw data.

As described above, when the MS imaging data for the entire measurement region 101 is stored in the data storage unit 20, when the user issues an instruction to perform analysis from the input unit 3, the data processing unit 2 executes the following processing.

First, the area division unit 21 in the data processing unit 2 performs a process of virtually dividing one measurement area 101 into multiple analysis areas 103 as shown in FIG. 4(A). In the example of FIG. 4(A), the rectangular measurement area 101 is divided into six, but the number of divisions is not limited to this. In addition, the division lines do not need to be straight lines. In addition, although the areas of the analysis areas 103 after division do not necessarily need to be the same, it is generally better not to make the difference in area too large, and one analysis area 103 includes multiple micro areas 102. In the example of FIG. 4, the six analysis areas 103 are labeled #1, #2, #3, #4, #5, and #6 to distinguish them from one another.

Next, the profile spectrum creation unit 22 sequentially reads out data corresponding to all of the microregions 102 contained in each analysis region 103 from the data storage unit 20, and creates a profile spectrum corresponding to each of the microregions 102. As shown in Figure 2, the profile spectrum is a continuous waveform in the m/z axis direction, and compounds present in the microregions 102 are observed as mountain-shaped peaks.

In conventional imaging mass spectrometers, one average mass spectrum is calculated for the measurement region 101 by averaging all of the profile spectra obtained in all of the microregions 102 within the measurement region 101. In contrast, in the imaging mass spectrometer of this embodiment, the spectrum averaging unit 23 executes a process for each analysis region 103 to average the profile spectra in all of the microregions 102 contained in one analysis region 103 (see FIG. 4(B)). Therefore, the same number of average mass spectra as the number of analysis regions 103, six in this example, are obtained.

3, a relatively high concentration of compound A is present over a relatively wide range within measurement region 101, while a relatively low concentration of compound B is present locally in a portion of measurement region 101. In such a case, if the profile spectra in all the micro-regions contained in measurement region 101 are averaged, the signal intensity of the peak corresponding to compound B will be significantly lower than the signal intensity of the peak corresponding to compound A, and if the m/z values of both are close, the peak corresponding to compound B may be buried in the tail of the peak corresponding to compound A.

In contrast, if the measurement region 101 is divided into multiple analysis regions 103 as shown by the dotted line in Figure 3 and the profile spectra of the microregions 102 contained in each analysis region 103 are averaged, the peak corresponding to compound B is more likely to be observed in the average spectrum obtained in some of the analysis regions 103 without being obscured by the peaks of compound A.

The peak information collecting unit 24 detects peaks in the average mass spectrum for each analysis region 103 according to a predetermined criterion (see FIG. 4(C)). Then, for each analysis region 103, information on the detected peaks is collected to create a peak list (see FIG. 4(D)). The peak information includes at least the m/z value of the peak, and may also include the intensity of the peak. As described above, since peaks derived from compound B contained locally in a part of the measurement region 101 are also observed in the average mass spectrum of some analysis regions 103, the peak list corresponding to the analysis region 103 may also include peak information of such compound B.

Next, the peak information integration unit 25 collects peak lists for all the analysis regions 103 and integrates the peak information (see FIG. 4E). Specifically, for example, the m/z values of the peaks listed in all the peak lists are arranged in ascending order, and if the difference between the m/z values of two or more adjacent peaks is within the m/z error determined according to the mass accuracy of the device used for the measurement, the peaks are considered to be from the same compound and integrated. When integrating multiple peaks with very close m/z values, the m/z value of any one of the multiple peaks before integration may be used as the m/z value of the integrated peak, or the m/z value calculated by a predetermined calculation from the m/z values of the multiple peaks before integration may be used as the m/z value of the integrated peak.

The peak information integration unit 25 creates an organized peak list for the entire measurement region 101 by integrating all peaks that can be integrated as described above (see FIG. 4(F)). Peak information corresponding to a compound that is widely distributed in the measurement region 101, such as compound A shown in FIG. 3, is listed in the peak list corresponding to multiple analysis regions 103. Although the peak information may differ slightly depending on the analysis region 103, the difference should be within the error range of the mass accuracy of the device, so the peaks are integrated. On the other hand, peak information corresponding to a compound that is locally distributed in the measurement region 101, such as compound B shown in FIG. 3, is listed only in the peak list corresponding to one analysis region 103, but this is also reflected in the integrated peak list.

The peak list display processing unit 26 displays the peak list for the entire measurement region 101 created as described above on the screen of the display unit 4. Alternatively, the peak list display processing unit 26 may create a mass spectrum (hereinafter referred to as an integrated mass spectrum) based on the peak list created as described above and display this integrated mass spectrum (see FIG. 4(G)).

The user checks the displayed peak list or integrated mass spectrum on the screen and, for example, selects a desired peak on the peak list or integrated mass spectrum by indicating it with the input unit 3. The peak selection instruction receiving unit 27 recognizes the indicated peak and determines the m/z value associated with that peak.

The MS imaging image creation unit 28 reads out the signal intensity values for each microregion 102 corresponding to the determined m/z value from the data storage unit 20, and creates an MS imaging image. The image display processing unit 29 displays the created MS imaging image on the screen of the display unit 4. For example, the MS imaging image is displayed on the same screen as the peak list or integrated mass spectrum, and when the user changes the peak specified on the peak list or integrated mass spectrum, the displayed MS imaging image can be quickly updated in response to the change in specification (change in the specified m/z value).

In this way, the imaging mass spectrometer of this embodiment can present the user with a peak list and/or an integrated mass spectrum that fully reflects information about ion peaks derived from various compounds present globally or locally within the measurement region 101. This allows the user to appropriately select a peak that corresponds to a compound of interest on the integrated mass spectrum and confirm an MS imaging image that shows the distribution of that compound with high accuracy.

In the imaging mass spectrometer of the above embodiment, the region dividing unit 21 automatically divides the measurement region 101 into multiple regions according to a predetermined rule, but the user may be able to set the rule as appropriate. Also, instead of dividing the entire measurement region 101, it is possible to divide only a specific range within the measurement region 101 designated by the user, for example, to define multiple analysis regions, and then perform the above-mentioned processing on the multiple analysis regions.

Furthermore, the user may be allowed to manually specify multiple analysis regions themselves within the measurement region 101. Figure 5 shows a modified example when multiple analysis regions are set manually within the measurement region 101.

For example, the region division unit 21 displays an optical microscope image of the entire measurement region 101, and accepts the user's specification of multiple analysis regions on the display screen. In the example of FIG. 5, four analysis regions 104A-104D are specified. Here, the shape of each analysis region is rectangular, but this is not limited to this. The size, position, and number of analysis regions are also arbitrary. The analysis regions 104A-104D specified in this way can be treated as they are in the same way as the analysis regions after automatic division, and processing can be continued. By making it possible to set the analysis region by such manual operation, for example, a specific part that can be observed in the optical microscope image (such as a biological tissue or a lesion site) can be processed as one analysis region, which is useful for understanding compounds that are usually easy to overlook.

In the imaging mass spectrometer of the above embodiment, the imaging mass spectrometer 1 uses a time-of-flight mass separator as a mass separator, but it is not limited to a time-of-flight mass separator, and it is preferable to use a mass separator having a mass resolution equivalent to or higher than that. Specifically, in addition to various time-of-flight mass spectrometers, Fourier transform mass spectrometers using a Fourier transform ion cyclotron resonance mass separator, an orbitrap mass separator, etc. are useful. In addition, the ion source in the imaging mass spectrometer 1 is not limited to an atmospheric pressure MALDI ion source, and an ion source using any ionization method can be used.

In addition, the imaging mass spectrometry unit 1 may perform mass analysis by sequentially scanning the micro-areas 102 set in the measurement area 101 on the sample 100, but may perform projection-type (or projection-type) imaging mass spectrometry in which mass analysis is performed simultaneously on multiple micro-areas in parallel. Furthermore, the imaging mass spectrometry unit 1 may physically cut out minute sample pieces from each of the micro-areas 102 in the measurement area 101 by a technique such as laser microdissection, and obtain data by mass analyzing liquid samples prepared from each of the sample pieces. In other words, the measurement technique may be one that can obtain mass spectrum data in a predetermined m/z range in each of the micro-areas 102 in the measurement area 101.

Furthermore, the above-mentioned embodiment and modified examples are merely examples of the present invention, and it goes without saying that any appropriate modifications, amendments, additions, etc. made within the spirit of the present invention will also be encompassed within the scope of the claims of the present application.

[Various aspects]
It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

(Item 1) One aspect of a mass spectrometry data analysis method according to the present invention is a mass spectrometry data analysis method for analyzing data obtained by performing mass spectrometry on each of a plurality of micro-areas within a measurement area on a sample, the method comprising:
an analysis region determination step of determining a plurality of analysis regions each including a plurality of the microregions by dividing the measurement region or in response to a user's designation within the measurement region;
a spectrum calculation step of averaging or integrating profile spectra for each of a plurality of micro-regions included in one analytical region based on data obtained for the micro-regions in each of the plurality of analytical regions to obtain an individual integrated mass spectrum;
a peak information integration step of detecting peaks in each of the plurality of individual integrated mass spectra, collecting peak information including at least the mass-to-charge ratio values of the detected peaks in each of the plurality of analysis regions, and collecting the peak information of the plurality of analysis regions and arranging peaks that can be estimated to have substantially the same mass-to-charge ratio value to obtain integrated peak information;
an information display step of creating and displaying a peak list or a mass spectrum based on the integrated peak information;
has.

(Item 4) One aspect of the imaging mass spectrometer according to the present invention is
a measurement unit for acquiring data by performing mass spectrometry on each of a plurality of micro-areas within a measurement area on a sample;
an analysis region determination unit that determines a plurality of analysis regions each including a plurality of the microregions by dividing the measurement region or in response to a user's designation within the measurement region;
a spectrum calculation unit that averages or integrates profile spectra based on data obtained by the measurement unit for a plurality of micro-areas included in each of the plurality of analysis regions to obtain an individual integrated mass spectrum;
a peak information integration unit that performs peak detection for each of the plurality of individual integrated mass spectra, collects peak information including at least the mass-to-charge ratio value of the detected peak in each of the plurality of analysis regions, and collects the peak information of the plurality of analysis regions and organizes peaks that can be estimated to have substantially the same mass-to-charge ratio value to obtain integrated peak information;
a display processing unit that creates a peak list or a mass spectrum based on the integrated peak information and displays it on a display unit;
Equipped with.

In the mass analysis data analysis method described in paragraph 1 and the imaging mass spectrometer described in paragraph 4, the profile spectrum is averaged or integrated for each analysis region, which is a smaller area than the entire measurement region where the data was collected, and integrated peak information is obtained based on the results. This makes it possible to prevent peaks derived from compounds that are present locally in relatively small amounts in the measurement region from being buried in the tails of other peaks with similar m/z values and high intensities, and to provide the user with a peak list or mass spectrum that accurately reflects such peaks. As a result, according to the above-mentioned aspect of the present invention, the user can accurately analyze the target compound without overlooking the presence of compounds that are present locally in small amounts in a narrow range in the measurement region.

Furthermore, the mass analysis data analysis method described in paragraph 1 and the imaging mass spectrometer described in paragraph 4 can take advantage of the high mass accuracy of the mass spectrometer used for the measurement, and display a mass spectrum in which peaks of m/z values corresponding with high accuracy to the masses of multiple compounds present in the measurement region can be observed. This allows the user to observe high-precision MS imaging images corresponding to each of the multiple compounds, and allows for more detailed and accurate compound distribution analysis than ever before.

(2) The mass spectrometry data analysis method according to the first aspect of the present invention comprises:
a peak selection receiving step of receiving an instruction for selecting a peak by a user on the peak list or mass spectrum displayed by the information display step;
generating a mass spectrometry imaging image corresponding to the indicated peak;
The present invention may further include the following:

In the peak list or mass spectrum displayed by the display step in the mass spectrometry data analysis method described in paragraph 1, highly accurate peaks corresponding to the multiple compounds present in the measurement region or m/z value information of the peaks can be obtained. According to the mass spectrometry data analysis method described in paragraph 2, the user can specify a specific peak based on this peak list or mass spectrum to display an MS imaging image, so that an MS imaging image that reflects the distribution of the target compound with high accuracy can be displayed. In addition, the user can check the distribution of compounds that are present in only small amounts locally in the measurement region without overlooking them using the MS imaging image.

(Clause 3) In the mass spectrometry data analysis method described in paragraph 1 or 2, the peak information integration step may include carrying out a process to determine whether the mass-to-charge ratio values of multiple peaks are substantially identical, according to a criterion corresponding to the mass accuracy of the device used for mass spectrometry.

The mass spectrometry data analysis method described in paragraph 3 makes full use of the high mass accuracy of the device, and can accurately provide the user with information on peaks derived from multiple different compounds with very close m/z values as separate peaks. In addition, peaks that have different m/z values but are presumed to be derived from the same compound can be integrated and provided to the user as information on a single peak, thereby avoiding providing the user with unnecessary and redundant information.

REFERENCE SIGNS LIST 1 Imaging mass spectrometry section 2 Data processing section 20 Data storage section 21 Region division section 22 Profile spectrum creation section 23 Spectral averaging section 24 Peak information collection section 25 Peak information integration section 26 Peak list display processing section 27 Peak selection instruction acceptance section 28 MS imaging image creation section 29 Image display processing section 3 Input section 4 Display section

Claims (4)

A mass spectrometry data analysis method for analyzing data obtained by performing mass spectrometry on each of a plurality of micro-areas within a measurement area on a sample, comprising:
an analysis region determination step of determining a plurality of analysis regions each including a plurality of the microregions by dividing the measurement region or in response to a user's designation within the measurement region;
a spectrum calculation step of averaging or integrating profile spectra for each of a plurality of micro-regions included in one analytical region based on data obtained for the micro-regions in each of the plurality of analytical regions to obtain an individual integrated mass spectrum;
a peak information integration step of detecting peaks in each of the plurality of individual integrated mass spectra, collecting peak information including at least the mass-to-charge ratio values of the detected peaks in each of the plurality of analysis regions, and collecting the peak information of the plurality of analysis regions and arranging peaks that can be estimated to have substantially the same mass-to-charge ratio value to obtain integrated peak information;
an information display step of creating and displaying a peak list or a mass spectrum based on the integrated peak information;
A mass spectrometry data analysis method comprising the steps of: a peak selection receiving step of receiving an instruction for selecting a peak by a user on the peak list or mass spectrum displayed by the information display step;
generating a mass spectrometry imaging image corresponding to the indicated peak;
The method of claim 1 , further comprising: The mass spectrometry data analysis method according to claim 1, wherein the peak information integration step performs a process to determine whether the mass-to-charge ratio values of multiple peaks are substantially identical according to a criterion corresponding to the mass accuracy of the device used for mass spectrometry. a measurement unit for acquiring data by performing mass spectrometry on each of a plurality of micro-areas within a measurement area on a sample;
an analysis region determination unit that determines a plurality of analysis regions each including a plurality of the microregions by dividing the measurement region or in response to a user's designation within the measurement region;
a spectrum calculation unit that averages or integrates profile spectra based on data obtained by the measurement unit for a plurality of micro-areas included in each of the plurality of analysis regions to obtain an individual integrated mass spectrum;
a peak information integration unit that performs peak detection for each of the plurality of individual integrated mass spectra, collects peak information including at least the mass-to-charge ratio value of the detected peak in each of the plurality of analysis regions, and collects the peak information of the plurality of analysis regions and organizes peaks that can be estimated to have substantially the same mass-to-charge ratio value to obtain integrated peak information;
a display processing unit that creates a peak list or a mass spectrum based on the integrated peak information and displays it on a display unit;
An imaging mass spectrometer comprising:

Images